Flow-path controllers and related systems

ABSTRACT

An observed operational state can include an operational state of one or more system devices. A sensor can emit, in response to a detected observable condition reflective of a given operational state, a simulated signal reflective of a different operational state as a proxy for the detected condition. A controller receiving such a proxy signal can, at least partially responsively to the proxy signal, issue a command corresponding to the given operational state. An electro-mechanical actuator can be selectively activatable responsive to the command.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of and priority to U.S. PatentApplication No. 62/256,519, filed Nov. 17, 2015, and claims benefit ofand priority to, as a continuation-in-part of, co-pending U.S. patentapplication Ser. No. 14/777,510, filed Sep. 15, 2015, which is a U.S.National Phase Application of International Patent Application No.PCT/IB2014/059768, filed Mar. 14, 2014, which claims benefit of andpriority to U.S. Patent Application No. 61/793,479, filed Mar. 15, 2013,U.S. Patent Application No. 61/805,418, filed Mar. 26, 2013, U.S. PatentApplication No. 61/856,566, filed Jul. 19, 2013, and U.S. PatentApplication No. 61/880,081, filed Sep. 19, 2013, each of which patentapplications is hereby incorporated by reference in its entirety as iffully set forth herein, for all purposes.

Other pertinent disclosures include U.S. Patent Application No.61/522,247, filed Aug. 11, 2011, U.S. Patent Application No. 61/622,982,filed Apr. 11, 2012, U.S. Patent Application No. 61/794,698, filed Mar.15, 2013, U.S. patent application Ser. No. 13/559,340, filed Jul. 26,2012, now U.S. Pat. No. 9,496,200, U.S. Patent Application No.61/908,043, filed Nov. 23, 2013, and U.S. patent application Ser. No.14/550,952, filed Nov. 22, 2014, each of which patent applications ishereby incorporated by reference in its entirety as if fully set forthherein, for all purposes.

BACKGROUND

The innovations and related subject matter disclosed herein(collectively referred to as the “disclosure”) pertain to control offluid-flow paths in heat-transfer systems, and more particularly, butnot exclusively, to electro-mechanically actuated flow-path controllers,with automatically decoupleable couplers and electro-mechanicallyactuated valves being but two specific examples of disclosed flow-pathcontrollers. Such actuators can be activated responsively to an alert ora command received from a controller. Such controllers can issue thealert or command, for example, in response to a detected change in stateof a given system. For example, a leak detector can be configured torespond to a detected leak of a working fluid from a liquid-based heattransfer system, or a flow-rate sensor can be configured to detect arate of flow of a fluid through a conduit. In either instance, acontroller can issue an alert or a command over a bus responsively to adetected change in state (e.g., a detected leak or a detected change inflow rate). Responsive to such an alert or a command, one or moreelectro-mechanical actuators, such as, for example, a linear or a rotaryservo- or stepper-motor, can urge or pull against a linkage or othermember arranged to terminate a fluid flow through a conduit, a channel,or other flow path. In particular examples, such an electro-mechanicalactuator can cause one or more valves to open or to close, or cause apair of matingly engaged couplers (sometimes referred to in the art as,for example, a “dripless quick-connect” or a “quick-disconnect”) todecouple from each other. Some detectors and control systems aredescribed in relation to cooling systems for electronic devices by wayof example. Nonetheless, one or more of the innovations disclosed hereincan be suitable for use in a variety of other control-systemapplications, as will be understood by those of ordinary skill in theart following a review of the present disclosure.

Computer system performance and heat dissipation density continue toincrease. Consequently, conventional air-cooling is giving way toliquid-cooling in some computer system applications, including, but notexclusively, server and data center applications. Although commerciallyavailable liquid cooling systems are considered to be reliable and toprovide known and repeatable performance, an automated approach fordetecting an unlikely leak might be desirable in some applications.However, commercially available moisture sensors and leak detectors arenot compatible with existing control systems for computer systems.

Also, approaches for monitoring a rate of flow of a fluid through one ormore conduits might be desirable in some applications. For example, arate of heat transfer through a liquid-to-liquid or an air-to-liquid (ora liquid-to-air) heat exchanger can correspond to a rate of flow of aheat transfer medium (e.g., a liquid coolant) through the heatexchanger. As but one other example, a substantial excursion of fluidflow rate through a conduit can indirectly indicate a leak upstream ofthe conduit, or a change in heat-transfer performance.

However, many commercially available flow-rate sensors are generallyconsidered to be incompatible with existing liquid-cooling systemssuitable for computer systems. For example, some known flow-rate sensorsare typically too large, too expensive, or both, to be incorporated intoliquid-cooling systems suitable for widespread commercialization inconnection with cooling systems for computer systems, or other systems.

Commercially available, liquid-based heat-transfer systems, particularlybut not exclusively liquid- or two-phase-cooling systems forelectronics, have not provided controllable, reconfigurable, orcustomizable arrangements of fluid flow paths once a given heat-transfersystem has been installed. Nonetheless, controllable, reconfigurable, orcustomizable fluid-flow paths can be desirable in some instances, aswhen a leak is detected and/or a detected flow rate through a particularconduit, channel, or other fluid passage exceeds or falls below aselected threshold. For example, automatically isolating a branch offluid circuit responsive to a detected leak could be desirable in anattempt to avoid damage to, for example, nearby electronic components.

Accordingly, there remains a need for sensors configured to detect aleak from a liquid cooling system. There also remains a need for amonitoring system configured to initiate an alert responsive to a leakdetected by the leak detector. A need also remains for a leak detectorconfigured to be compatible with a control system for a computer systemor other computing environment. And, there remains a need for flow-ratesensors configured to detect or sense a rate of flow of a working fluidthrough a conduit, for example, a portion of a flow path through aportion of a liquid-cooling system. There remains a further need forflow sensors to emit a signal responsive to a detected or a sensed flowrate of the working fluid. There also remains a need for such sensors tobe compatible with existing communications busses, e.g., by usingexisting communication protocols or by multiplexing over existingcommunication busses (e.g., an IPMI bus). As well, a need remains forapparatus and methods for controlling, reconfiguring, and/or customizinga flow path through a given heat-transfer system. In addition, a needremains for apparatus and methods for isolating one or more branches ofa fluid circuit.

SUMMARY

Innovations and related subject matter disclosed herein overcome manyproblems in the prior art and address one or more of the aforementioned,or other, needs. This disclosure pertains generally to control systems,for example, detectors configured to issue an alert or a command to acontroller in response to a detected change in state of a given system,electro-mechanically actuated flow-path controllers, with automaticallydecoupleable couplers and electro-mechanically actuated valves being buttwo specific examples of disclosed flow-path controllers, andcombinations thereof.

By way of example, a disclosed control system has a sensor circuitconfigured to emit a simulated signal corresponding to a selectedphysical parameter as a proxy for an observed operational parameterdifferent from the selected physical parameter. A controller isconfigured to receive the simulated signal and to infer from thesimulated signal a state of the observed operational parameter. Anelectro-mechanical actuator is selectively activatable based at least inpart on the inferred state of the observed operational parameter.

The controller can be configured to emit a command signal responsive tothe state of the observed operational parameter and theelectro-mechanical actuator can be selectively activatable responsivelyto the command signal. The simulated signal can be a simulatedfan-tachometer signal, and the selected physical parameter can be a fanspeed. In some examples, the sensor is a leak detector, and the observedoperational parameter is a detected presence or a detected absence of aleak by the leak detector. The simulated signal can be, for example, asimulated reproduction of a waveform emitted by a properly or animproperly operating, or a failed, fan.

The selected physical parameter can be a rotational fan speed and theobserved operational parameter can consist of one or more of an indiciaof fluid level, an indicia of pressure, an indicia of electricalcurrent, and an indicia of a presence or absence of moisture.

The observed operational parameter can be an indicia of a presence orabsence of a working fluid externally of a liquid-based heat-transfersystem. The sensor can include an electrical circuit configured to emitthe simulated signal responsive to the indicia of a presence of theworking fluid externally of the liquid-based heat transfer system, andthe electro-mechanical actuator can be configured to decouple matinglyengaged couplers or to close a valve to isolate a branch of a fluidcircuit.

In other examples, methods of isolating a branch of a fluid circuit froma liquid-based heat-transfer system are disclosed. A presence or anabsence of a working fluid can be sensed externally of a liquid-basedheat-transfer system. An electro-mechanical actuator can be activated toclose a valve and/or to decouple matingly engaged members of a fluidcoupler.

For example, a signal can be emitted responsive to the sensed presenceor absence of the working fluid. The emitted signal in the sensedabsence of the working fluid can be, for example, a simulated tachometersignal of the type emitted by an operable fan.

Rack-mountable server systems are disclosed. In such a system, a branchof a fluid circuit can be configured to convey a liquid from an inlet tothe branch to an outlet from the branch. The inlet and the outlet can befluidly coupled with a liquid supply and a liquid collector,respectively. A sensor can be configured to detect a presence of theworking fluid externally of the branch, and an electro-mechanicalactuator can be configured to fluidly isolate the branch from the fluidcircuit responsive to a detected presence of the working fluidexternally of the branch.

Some disclosed rack-mountable server systems also include an electricalcircuit operatively coupled to the sensor and being configured to emit asignal responsive to a detected presence of the liquid externally of theconduit. The electro-mechanical actuator can be actuatable responsive tothe signal. The electro-mechanical actuator can be configured to closeone or more valves and/or to decouple matingly engaged members of afluid coupling. For example, a linkage can couple the electromechanicalactuator to one or more of the valves and/or to a movable portion of thematingly engaged members.

Some rack-mountable server systems also include a server rack and aplurality of independently operable servers received in the rack. Theliquid supply can be a distribution manifold and the liquid collectorcan be a collection manifold. The branch of the fluid circuit can be abranch of a heat-transfer system corresponding to a first server and theelectro-mechanical actuator can be a first electro-mechanical actuatorcorresponding to the first server. Each other server can have acorresponding branch of the heat-transfer system with an inlet fluidlycoupled to the distribution manifold and an outlet fluidly coupled tothe collection manifold. A plurality of electro-mechanical actuators caneach correspond to one of the other servers and each be configured tofluidly isolate each respective branch from the heat-transfer system.

The inlet to each branch of the heat-transfer system can have a firstmember of a decoupleable fluid coupling and the distribution manifoldcan have a second member of the decoupleable fluid couplingcorresponding to each branch. Each respective first member andcorresponding second member can be so correspondingly configured as tobe matingly engageable with each other. As well, each respectiveelectro-mechanical actuator can be configured to decouple the respectivematingly engaged first member and second member from each other.

Some disclosed rack-mountable server systems have a plurality of valves.Each valve can be positioned adjacent a corresponding one of the branchinlets. Each valve can be selectively activatable by the correspondingelectro-mechanical actuator. Each branch can also have one or more checkvalves. For example, a check valve can be positioned adjacent acorresponding one of the branch outlets and be configured to prevent abackflow of a working fluid from the collection manifold into therespective branch of the heat-transfer system.

A rack-mountable server system can have a printed circuit board, and thesensor can be a sensitive region operatively coupled to the printedcircuit board at a position adjacent a component susceptible to wettingby the liquid if a leak of the liquid from the branch occurs

Some disclosed detectors are configured to emit a simulated signal(e.g., an electrical signal) as a proxy for a state observed by asensor, with a simulated fan-tachometer signal being but one example ofa proxy signal.

Some disclosed detectors are configured to detect a leak of a workingfluid from a heat-transfer system. Some disclosed leak detectors areconfigured to issue an alert or a command to a controller in response toa detected leak of a working fluid from a liquid-based heat transfersystem.

Some disclosed detectors are configured to assess one or more aspects ofa flow field, e.g., to assess a flow rate. Some disclosed detectors areconfigured to detect a flow rate of a working fluid through a portion ofa heat-transfer system. Some disclosed flow-rate sensors are configuredto emit a signal, or to issue an alert or a command to a controller inresponse to an observed or a detected change in state of a given system.

For example, some disclosed flow-rate sensors are configured to emit asignal, or to issue an alert or a command to a controller in response toan observed or a detected rate of flow (or an indicia of a rate of flow)of a working fluid through a liquid-based heat transfer system, as whenan observed, detected, or indicated rate of flow exceeds a selectedupper threshold flow rate or falls below a selected lower threshold flowrate. Some flow-rate sensors are configured to emit an output signalcorresponding to an observed rate of flow (or an observed indiciathereof).

By way of example and not limitation, a flow-rate sensor can beconfigured to emit a simulated fan-tachometer signal (or other proxysignal) proportional to (or, more broadly, corresponding to) an indiciaof flow rate observed by the sensor. A controller configured to receivesuch a simulated fan-tachometer signal can interpret the simulatedfan-tachometer signal as corresponding to a predetermined measure of theindicia of flow rate (or measure of the flow rate). In response, thecontroller can issue a system command in correspondence to the indicia(or flow rate). As but one example, the system command can be a commandto transmit an alert to a system administrator and/or a command toincrease pump speed, as when the indicated flow rate might not sufficeto cool an observed or an anticipated heat load, or to decrease pumpspeed, as when the indicated flow rate might provide more cooling thannecessary based on an observed or an anticipated heat load and continuedoperation of the pump at a relatively higher speed emits more acousticnoise or consumes more energy than desired.

In some embodiments, an emitted signal, or an alert or command, includesa simulated fan-tachometer signal corresponding to a selectedfan-rotational-speed as a proxy for an observed state different than afan-rotational-speed (e.g., a flow rate or a detected leak). Forexample, an observed operational state can include an operational stateof one or more system devices (e.g., a pump in a liquid-cooling system,a heat exchanger in a liquid cooling system, a frequency of an opticalsignal emitted by an optical emitter, an observed flow rate through oneor more portions of a cooling system (e.g., through a segment of aconduit carrying a working fluid), etc.).

As but one possible and non-limiting example, a sensor can emit, inresponse to a detected one of a plurality of observable conditions, asimulated fan-tachometer signal corresponding to a respectivefan-rotational speed as a proxy corresponding to the detected condition.For example, a leak detector can emit, in response to a detected leak, asimulated fan-tachometer signal corresponding to a fan-rotational-speedof 500 RPM (revolutions per minute). In turn, the fan rotational speedof 500 RPM can be interpreted by a controller as indicating, forexample, that a leak has occurred (or at least has been detected) at agiven system location.

As another example, a flow-rate sensor can emit, in response to a firstobserved flow rate (or an observed indicia of such a flow rate), asimulated fan-tachometer signal corresponding to a firstfan-rotational-speed and a second fan rotational speed in response to anobserved other flow rate (or indicia thereof). For example, theflow-rate sensor can emit a simulated fan-tachometer signal indicativeof a selected fan speed proportional to the observed flow rate (orindicia thereof). A controller that receives such a proxy signal can, atleast partially responsively to the proxy signal, issue a selectedcommand (e.g., a system command to alter or to maintain a systemoperational state, a system shut-down command, an administrator alertcommand) responsive to a given interpretation of the proxy signal.

Some controllers are embodied in a computing environment.

As used herein, “working fluid” means a fluid used for or capable ofabsorbing heat from a region having a relatively higher temperature,carrying the absorbed heat (as by advection) from the region having arelatively higher temperature to a region having a relatively lowertemperature, and rejecting at least a portion of the absorbed heat tothe region having a relatively lower temperature. Although manyformulations of working fluids are possible, common formulations includedistilled water, ethylene glycol, propylene glycol, and mixturesthereof.

Some disclosed leak detectors include a sensor operatively coupled to aleak detector circuit. A leak detector circuit can be configured todeliver a signal having a selected waveform to a monitor circuit duringnormal operation of the cooling system and to terminate or otherwiseinterrupt the signal (as by modifying the waveform, for example) when aleak of liquid is detected, as by the sensor. Some disclosed leakdetectors are configured to deliver a simulated tachometer signal to amonitor circuit or computing environment. The simulated tachometersignal can be similar to a tachometer signal emitted by a fan duringnormal operation of the fan until a leak is detected. Upon receiving asignal or other indication of a leak, the leak detector circuit can emita different signal (or no signal) after a leak is detected. Thedifferent signal can be emitted continuously or only while a leak (ormoisture or other proxy for a leak) is detected by the sensor.

For example, some disclosed leak detector circuits are configured toemit a simulated tachometer signal, e.g., a square wave having a dutycycle of about 50% (e.g., a duty cycle ranging from about 45% to about55%), during normal operation, and to terminate or otherwise interruptthe simulated tachometer signal in response to a detected leak (ormoisture or other proxy for a leak, such as a low operating pressure ora low-fluid level internal to the heat-transfer system). Such a leakdetector circuit can be compatible with commercially available monitorcircuits, firmware and/or software, particularly but not exclusively,monitor circuits, firmware and/or software configured to monitor arotational speed of a fan using a tachometer signal emitted by the fan.Some monitors (e.g., circuits and/or computing environments) can bebased on, by way of example, the Intelligent Platform ManagementInitiative (IPMI) specification, ver. 1.5/2.0 (described more fullybelow).

In some embodiments, a plurality of sensors or detectors can beoperatively coupled to a given communication circuit, and a controllercan configured to monitor the given communication circuit. Eachrespective sensor or detector in the plurality of sensors or detectorscan be configured to emit any of a plurality of discrete, simulatedsignals as respective proxies for a plurality of selected, detectableoperational states. For example, the sensors or detectors can emitdiscrete, simulated fan-tachometer signals corresponding to respectivesystem operational states. Such multiplexing can allow existingcommunication channels to carry information regarding observed systemoperational states that differ substantially from the informationhistorically carried by the existing communication channels.

By way of example and not limitation, a leak detector can be configurednot to emit a simulated fan-tachometer signal in the absence of anobserved leak, and to emit (e.g., over a selected communicationcircuit), responsively to a detected leak, a selected simulatedfan-tachometer signal (e.g., a simulated fan-tachometer signalcorresponding to a fan-rotational speed of 200 RPM). A controllerconfigured to receive such a simulated fan-tachometer signal caninterpret the simulated fan-tachometer signal as corresponding to apredetermined operational state. In response, the controller can issue asystem command in correspondence with the operational state. As but oneexample, the system command can be a command to transmit an alert to asystem administrator or a command to shut the system down.

As another example, a sensor can be configured to observe an operationalstate of a centrifugal pump. The sensor can be configured to emit asimulated fan-tachometer signal corresponding to a differentfan-rotational speed (e.g., 400 RPM) in response to an observed pumpfailure (e.g., a pump rotational speed below a selected thresholdrotational speed). A controller configured to receive the simulatedfan-tachometer signal can issue a system command in response to andcorresponding to the indication of a pump failure. The system commandcan include one or more of a command to transmit an alert to a systemadministrator, a command to increase a rotational speed of one or moreother selected pumps, and a command to shut the system down.

Other particular but non-exclusive examples of multiplexed sensorsinclude sensors configured to observe one or more of a rotational speedof the pump, a static pressure in a fluid within the pump, a temperatureof a liquid in the pump, a temperature of a pump component, a flow ratethrough a conduit, and a number of hours during which a given pump hasoperated. Each sensor can be configured to emit a selected proxy signalcorresponding to an observed operational state of the system.

Other innovative aspects of this disclosure will become readily apparentto those having ordinary skill in the art from a careful review of thefollowing detailed description (and accompanying drawings), whereinvarious embodiments of disclosed innovations are shown and described byway of illustration. As will be realized, other and differentembodiments of leak detectors and systems incorporating one or more ofthe disclosed innovations are possible and several disclosed details arecapable of being modified in various respects, each without departingfrom the spirit and scope of the principles disclosed herein. Forexample, the detailed description set forth below in connection with theappended drawings is intended to describe various embodiments of thedisclosed innovations and is not intended to represent the onlycontemplated embodiments of the innovations disclosed herein. Instead,the detailed description includes specific details for the purpose ofproviding a comprehensive understanding of the principles disclosedherein. Accordingly the drawings and detailed description are to beregarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Unless specified otherwise, the accompanying drawings illustrate aspectsof the innovative subject matter described herein. Referring to thedrawings, wherein like reference numerals indicate similar partsthroughout the several views, several examples of systems incorporatingaspects of the presently disclosed principles are illustrated by way ofexample, and not by way of limitation, wherein:

FIG. 1 shows a representative pulse of a square wave emitted by a Hallcell in response to a rotating fan rotor;

FIG. 2 shows a representative signal emitted by a fan in a runningstate, a locked rotor state, and another running state;

FIG. 3 shows a representative pin-out for a fan header operativelycoupled to a pump;

FIG. 4 shows a portion of but one of many leak detector embodimentsdisclosed herein;

FIG. 5 shows a block diagram of a leak detector and a portion of anassociated control system in relation to a fluid heat exchange system;

FIG. 6 shows a schematic illustration of an embodiment of a circuitconfigured according to the block diagram shown in FIG. 5;

FIG. 7 shows a pinout of a fan header operatively coupled to anembodiment of a leak detector disclosed herein;

FIG. 8 shows a schematic illustration of a system including a leakdetector disclosed herein; and

FIG. 9 shows a schematic illustration of an alternative system includinga leak detector disclosed herein;

FIG. 10 shows a schematic illustration of a cooling system having anoptical flow-rate sensor of the type disclosed herein;

FIG. 11 shows a schematic illustration of an optical flow-rate sensor;

FIG. 12 shows a schematic illustration of a retainer suitable for theoptical flow-rate sensor shown in FIG. 11:

FIG. 13 shows one possible configuration of a rotational member asdisclosed herein;

FIG. 14 shows a schematic illustration of an apparatus configured tocalibrate a flow-rate sensor of the type shown in FIG. 13;

FIG. 15 shows a plot of a calibration of a flow-rate sensor;

FIGS. 16A and 16B show respective schematic illustrations of arotational member of the type shown in FIG. 13; in FIG. 16A, a reflectoris shown; in FIG. 16B, the rotational member has rotated to a positionobscuring the reflector shown in FIG. 16A from view;

FIG. 17 shows a selected proxy relationship (or correlation) between anobserved flow rate of a working fluid (or indicia thereof) and a fanspeed indicated by a simulated fan-tachometer signal; and

FIG. 18 shows a block diagram of a computing environment suitable foruse in combination with systems, methods and apparatus described herein.

FIG. 19 illustrates a coupler of the type disclosed herein.

FIG. 20 contains a photograph of a working embodiment of a coolingsystem having automatically decoupleable couplers of the type shown inFIG. 19.

DETAILED DESCRIPTION

The following describes various innovative principles related to controlsystems by way of reference to specific examples of sensors, actuators,and couplers included in such systems. More particularly, but notexclusively, such innovative principles are described in relation toexamples of leak detectors configured to detect a leak of a workingfluid from a liquid-based heat transfer system (e.g., a liquid-basedcooling system for cooling one or more electronic components thatdissipate heat during operation), examples of flow-rate sensorsconfigured to observe a flow rate through a liquid-based heat-transfersystem, examples of decoupleable couplers, examples of actuatorsconfigured to actuate a decoupleable coupler, and related systems.Nonetheless, one or more of the disclosed principles can be incorporatedin various other control system embodiments to achieve any of a varietyof desired control system characteristics. Systems described in relationto particular configurations, applications, or uses, are merely examplesof systems incorporating one or more of the innovative principlesdisclosed herein and are used to illustrate one or more innovativeaspects of the disclosed principles.

Thus, control systems, sensors, leak detectors, flow-rate sensors,decoupleable couplers, actuators, and associated circuits, computingenvironments, firmware and/or software having attributes that aredifferent from those specific examples discussed herein can embody oneor more of the innovative principles, and can be used in applicationsnot described herein in detail, for example, to detect a leak of a fluid(e.g., a liquid, a gas, or a saturated mixture thereof) from, or toobserve a local speed of a flow of such a fluid through, a heat-transfersystem having any of a variety of flow configurations, such as acontained flow within a fluid conduit or a free-stream flow (e.g., aregion of a fluid flow sufficiently spaced from a fluid boundary as notto be influenced by the boundary). Such systems can be configured totransfer heat to or from laser components, light-emitting diodes,chemical reactants undergoing a chemical reaction, photovoltaic cells,solar collectors, power electronic components, electronic componentsother than microprocessors, photonic integrated circuits, and otherelectronic modules, as well as a variety of other industrial, militaryand consumer systems now known or hereafter developed. Accordingly,embodiments of detectors and related control systems not describedherein in detail also fall within the scope of this disclosure, as willbe appreciated by those of ordinary skill in the art following a reviewof this disclosure.

Overview

A wide variety of control systems have been proposed and used. In ageneral sense, control systems estimate or observe an attribute of agiven system under control of the control system. In response to theestimated or observed attribute, a control system can provide an outputcorresponding to the estimated or observed attribute in order to achievea desired system response. Controls systems (or portions thereof)disclosed herein can be implemented in a computing environment. Asindicated above and explained more fully below, some disclosed systemsare configured to detect a leak of a working fluid from, for example, aliquid-based heat-transfer system. Some disclosed systems are configuredto transmit an alert or other command in response to a detected leak.

Some disclosed sensors are configured to be backward compatible withexisting control systems. For example, some existing control systemsconfigured to monitor an operational status of a cooling fan for acomputer system are configured to emit a signal corresponding toobserved fan speeds, or to issue an alert or other command, when anobserved fan speed drops below a selected threshold.

Taking advantage of an installed base of such existing control systems,some disclosed sensors have a circuit configured to emit a firstsimulated tachometer signal corresponding to a first observed condition(e.g., similar to a tachometer signal emitted by a normally operatingfan) and to emit a different simulated tachometer signal correspondingto a second observed condition. In some instances, the different signalemitted in response to the second observed condition can be similar to atachometer signal emitted by a failed or failing fan (e.g., a fanoperating at an unacceptably low fan speed, or a fan having a lockedrotor).

Another example of an operational status includes a flow rate through aconduit. Some disclosed sensors emit a simulated fan tachometer signalin correspondence with an observed volumetric (or mass) flow rate (orindicia thereof, such as, for example, a rotational speed of arotational member within the flow of fluid).

An operational status can reflect a presence or absence of a detectedleak. Some disclosed leak detectors have a circuit configured to emit asimulated tachometer signal similar to a tachometer signal emitted by anormally operating fan when no leak is detected and to emit a differentsignal (or no signal) in response to a detected leak. The differentsignal emitted in response to a detected leak can be similar to atachometer signal emitted by a failed or failing fan (e.g., a fanoperating at an unacceptably low fan speed, or a fan having a lockedrotor).

Some disclosed systems incorporate a sensor configured to detect orobserve an indicia of a change in state of a heat-transfer system. Someindicia pertain to a rate of flow of a working fluid, for example,through a portion of a liquid-based heat-transfer system. Other indiciapertain to a leak of such a working fluid. Some disclosed systems areconfigured to transmit an alert or other command in response to athreshold condition observed or detected by such a sensor.

As but one example, some disclosed flow-rate sensors are configured toobserve (or to detect) a frequency at which a rotational member rotatesabout a selected axis of rotation in response to a passing flow of aworking fluid. As will be described more fully below, such a rotationalfrequency can correspond to a speed (and thus a rate of flow) at which aflow of a selected fluid passes by or over the rotational member.

Control Systems

By way of introduction, computer systems commonly include one or moreaxial fans for cooling an electronic component. A rate of heat transferfrom an electronic component or from a liquid-to-air heat exchanger(e.g., a radiator) to a stream of air passing over the component or theheat exchanger generally corresponds, in part, to a speed of the airstream. A speed of such an air stream generally corresponds to arotational speed of the fan.

Taking advantage of such a correspondence between a fan's rotationalspeed (sometimes expressed in units of “revolutions per minute” or“RPM”, and sometimes referred to as a “fan speed”) and a rate of coolingafforded to an electronic component or a heat exchanger, some computersystems include a control system configured to adjust a fan speed inresponse to an observed temperature (e.g., a temperature of anelectronic component). As an example, some control systems areconfigured to modulate a duty cycle of, for example, a square wave, andsome fans, in turn, are configured to adjust their fan speed incorrespondence with the modulated duty cycle.

In addition (or alternatively), some computer systems include a controlsystem configured to observe an output signal from a fan. Such an outputsignal can correspond to a rotational speed of the fan. For example, afan can include a Hall cell configured to emit a square wave having afrequency corresponding to a rotational speed of a rotating magneticfield generated by a rotating fan rotor. Such an emitted square wave canhave a duty cycle of about 50% when the rotor rotates at anapproximately constant speed. Since the frequency of the square wave cancorrespond to the rotational speed of the fan, such a square wave issometimes referred to as a “tachometer signal.” FIG. 1 illustrates onepulse from a typical tachometer output having a square wave waveform. Asanother example, FIG. 2 shows a representative waveform of a tachometeroutput for a fan that changes from an operating state (“Running”) havinga 50% duty cycle, to a “Locked rotor” state in which no tachometersignal (or a steady-state signal) is emitted because the fan rotor doesnot rotate, and back to an operating state (“Running”) having a 50% dutycycle.

In general, a control system can be configured to transmit an alert orother command in response to an observed signal exceeding a selectedupper threshold or falling below a selected lower threshold. Somecontrol systems are configured to resume monitoring the observed signalafter transmitting the alert or other command Other control systems(sometimes referred to in the art as a “latching system”) are configuredto continuously transmit an alert or other command.

Some existing control systems are configured to observe a tachometersignal emitted by a rotating fan and to emit a signal or otherwiseinitiate a system command (e.g., send an “alert”, or initiate a systemshut-down) in response to a selected change in state of a tachometersignal. A selected change of state of a tachometer signal can include adrop in frequency below a selected threshold (e.g., corresponding to anunacceptably low fan speed), a cessation of a tachometer signal or anemission of steady-state tachometer signal, as when a fan rotor stopsrotating. In relation to FIG. 2, such a control system can be configuredto emit a signal or otherwise initiate a system command if an observedsignal indicates that a fan is in a “locked rotor” state.

Some suitable control systems configured to monitor fan speed are basedon the Intelligent Platform Management Initiative (IPMI) specification,ver. 1.5/2.0. Generally, IPMI is a message-based, hardware-levelinterface specification. An IPMI subsystem can operate independently ofan operating system of a computer incorporating the IPMI subsystem,allowing a system administrator to manage the computer independently ofthe operating system (e.g., before the operating system boots, or whenthe computer is powered down). A Baseboard Management Controller (BMC)can include a specialized microcontroller configured to manage aninterface between the system management software and computer systemhardware.

Among many features, an IPMI subsystem can monitor a status of variousoperating parameters, including, for example, system temperatures, fanspeeds, chassis intrusion, etc. In some instances, an IPMI subsystem canbe configured to monitor a tachometer signal emitted by one or more fansand, when the tachometer signal indicates a fan speed below a selectedthreshold, the subsystem can emit an alert or other command.

Computer systems incorporating such control systems for fans commonlyinclude a plurality of electrical connectors, with each being configuredto operatively couple a fan to a corresponding plurality of circuitsconfigured, respectively, to power, control and monitor the fan. Forexample, such an electrical connector can have four electrical couplerscorresponding respectively to (A) a power supply circuit configured toconvey an electrical current for powering the fan motor; (B) anelectrical ground; (C) a pulse-width modulation circuit configured toconvey a pulse-width modulation signal (sometimes referred to as a “PWMsignal”) for controlling the fan; and (D) a sense circuit configured toconvey a tachometer signal corresponding to a fan speed (sometimesreferred to in the art more generally as a frequency generator signal,or an “FG” signal). Such an electrical connector is sometimes referredto in the art as a “header” or a “fan header”. FIG. 3 shows a typicalpinout for a header with annotations reflecting use of the header inconjunction with a pump.

Leak Detectors

A leak detector circuit can be configured to respond to a leak (e.g.,moisture or another selected proxy for a leak) of a working fluiddetected by a sensor. For example, an innovative leak detector circuitcan be configured to emit a first waveform in the absence of a detectedleak and to emit a second waveform responsive to a detected leak. Anysuitable sensor configured to detect a leak (or other proxy for a leak,e.g., moisture, presence of a working fluid at a position external to aheat-transfer system, a low pressure in the heat-transfer system, a lowfluid level in the heat-transfer system) can be used in connection withsuch an electrical circuit.

As but one of many possible examples of leak-detection sensors, aleak-detection sensor 5 can have a first leak-detection wire 10 and asecond leak-detection wire 20, as shown in FIG. 4. The first and thesecond leak-detection wires 10, 20 can comprise respective exposedtraces on a printed circuit board. As shown in FIG. 4, the firstleak-detection wire 10 can extend from a power plane, V₁. The secondleak-detection wire 20 can extend generally parallel to and spaced apartfrom the first leak-detection wire 10. A region in which the first andthe second wires 10, 20 are coextensive can define a leak-sensitiveregion 25 of the sensor.

A leak can be detected when an open circuit between the first and thesecond leak-detection wires 10, 20 is closed. For example, a drop 30 ofa leaked liquid can span a gap between the first and the secondleak-detection wires 10, 20 within the leak-sensitive region 25 of thesensor 5, electrically coupling the first and the second leak-detectionwires to each other.

When the circuit between such first and second leak-detection wires 10,20 is closed, the circuit of the leak detector 5 can emit acorresponding signal indicative of a detected leak. For example, whenthe first and the second leak-detection wires 10, 20 shown in FIG. 4 areelectrically coupled to each other, the second leak-detection wire 20can be pulled high (e.g., can have a voltage potential corresponding tothe voltage of the power plane, V₁), and can activate a relay 35. Whenthe illustrated relay 35 is activated, the latch 40 electricallycoupling the pump and the fan header to each other can be switched toopen (e.g., disconnect) the coupling between the pump and the fanheader. Such a disconnection of at least one coupling between the pumpand the header can serve as a signal to a monitoring system that a leakhas been detected. The monitoring system can in response initiate analert or a system command. In other instances, such a relay can close acircuit to activate an electro-mechanical actuator of the type describedherein, e.g., to physically disconnect or to otherwise isolate a branchof a fluid circuit of a heat-transfer system.

In FIG. 5, a leak detection sensor is schematically illustrated asextending from an integrated pump and heat exchanger assembly (sometimesreferred to in the art as a “Head Module”). U.S. patent application Ser.No. 12/189,476 and related priority patent applications, each of whichis incorporated herein in full, for all purposes, describe examples ofsuch Head Modules. The leak detection sensor 125, 125 a shown in FIG. 5has first and second leak-detection wires 110, 120 (referred to in FIG.6 as “Cable Conductor 1” and “Cable Conductor 2”, respectively) spacedapart from each other to form a gap 121. Such a leak detection sensor issometimes referred to in the art as a “Leak Detect Cable.” One or bothof the leak-detection wires 110, 120 can be partially or fully embedded(or otherwise surrounded by) a semi-conducting carrier. The first and/orthe second leak-detection wires 110, 120 can be formed from an alloy ofcopper.

A conductive fluid spanning the gap between the first and secondleak-detection wires 110, 120 can provide a “non-trivial” resistancebetween the first and the second leak-detection wires. As used herein, a“non-trivial resistance” means a finite resistance sufficient toelectrically couple the first and the second leak-detection wires toeach other. With a circuit configured as shown in FIG. 6, a non-trivialresistance between the first and the second leak-detection wires cansupply the analog Leak Sense line 122 with a non-zero voltage.

As indicated in FIG. 5, some leak detectors have a functional module 130(sometimes referred to in the art as a “Glue Module”) configured torespond to a leak detected by a leak detection sensor 125. The GlueModule shown in FIG. 5 can be configured to deliver a logic high signalto the FG line (labeled as “Output Tach” in FIG. 5) responsive to asignal indicative of a leak received over the Leak Sense line 122.

In some embodiments, the Glue Logic module is configured to monitor theLeak Sense line 122 continuously. In other embodiments, the Glue Logicmodule is configured to sample the Leak Sense line 122 at defined times(e.g., at selected intervals, or at selected intermittent times). TheGlue Logic can also be configured to transmit a signal over an EnableDetect line 123, and, as shown by way of example in FIG. 6, the LeakDetection Circuit 125 a can be configured to become operative inresponse to a signal received over the Enable Detect line 123.

A Glue Logic module can be configured to interrupt operation of a pumpmotor responsive to a signal received over the Leak Sense line 122indicative of the existence of a leak (e.g., an electrical couplingbetween the first and the second leak-detection wires). For example, aMotor Cutoff line 126 can carry a signal emitted by the Glue Logic, anda Motor Control Circuit 127 can respond to a signal received over theMotor Cutoff line 126 by interrupting power to the motor 128.Alternatively (or additionally), the Glue Logic can force an outputtachometer signal 129 (e.g., an FG signal) from the Head Module to alogic 0 (e.g., low logic) to signify to a monitoring system that therehas been a failure associated with the Head Module.

Many other leak-detection sensor and leak detector circuitconfigurations are possible. As but several examples, such sensors caninclude a capacitive moisture sensor, an optical sensor, an infraredsensor, a pressure sensor configured to observe a pressure within theheat-transfer system, a sensor configured to detect a low fluid level inthe heat-transfer system, and other sensors now known and hereafterdeveloped.

Some leak detectors can have an electrical circuit operatively coupledto an FG signal pin of a header and be configured, in the absence of adetected leak, to emit a simulated tachometer signal 129 having awaveform similar to a waveform emitted by a properly operating fan. FIG.7 shows a header operatively coupled to such an electrical circuit. Theelectrical circuit (not shown) can be further configured to emit asimulated tachometer signal 129 having a waveform similar to a failed orfailing fan in response to a detected leak of a liquid from aliquid-base heat-transfer system (e.g., when a circuit between first andsecond leak-detection wires is closed). Alternatively, the electricalcircuit can be configured to emit no tachometer signal, similar to a fanhaving a locked rotor (see FIG. 2) in response to a detected leak of aliquid from a liquid-based heat-transfer system.

As an example, a leak detector circuit 225 can be operatively coupled toan available fan header. In response to a detected leak, the simulatedsignal can be interpreted as by switching a relay as described above inrelation to FIG. 4.

Alternatively, a leak-detection sensor 225 can be operatively coupled toan electrical circuit associated with one or more pumps 210 of aliquid-based heat-transfer system. For example, such a pump 210 can beelectrically coupled to a header 231 having a power pin, a ground pin, aPWM pin and an FG pin. The power pin can be operatively coupled to thepump motor to convey an electrical current to the pump to operate thepump. The PWM pin be operatively coupled to a pump controller and conveya pump-control signal to the pump controller, e.g., to control a speedof the pump. The FG pin can convey monitor a tachometer signal emittedby the pump to a sensing circuit configured to monitor the pump (or fan)speed.

In one example (e.g., shown in FIG. 8), a leak detector circuit 225 canbe operatively coupled between the power pin of the header 231 and thepump motor 210. In such an embodiment, the leak detector circuit 225 caninterrupt a supply of electrical current to the pump (or increase asupply of electrical current to the pump) in response to a detectedleak, causing a corresponding reduction (or increase) in pump speed. Acorresponding FG signal emitted by the pump can reflect the diminished(or increased) pump speed. A system configured to monitor the FG signalemitted by the pump can, in response to a reflected change in pumpspeed, transmit an alert signal (e.g., to a system administrator), asystem command (e.g., a command to increase a pump speed of another pumpin an attempt to compensate for a diminished performance of a stalledpump, a system-shut-down command, etc.), or both. Some implementersmight elect not to interrupt power to a pump if stopping a pump might beconsidered a catastrophic failure.

In an alternative embodiment, a leak detector circuit 225 can beoperatively coupled between the PWM pin of the fan header 231 and thepump 210. In such an embodiment, the leak detector circuit 225 caninterrupt a PWM signal conveyed to the pump 210 by the PWM pin of thefan header and convey an alternative PWM signal (or no PWM signal) tothe pump in response to a detected leak. The alternative PWM signal cancause the pump to speed up, to slow down, or to stop. An FG signalemitted by the pump can reflect the change in pump speed. A systemconfigured to monitor the FG signal emitted by the pump can, in responseto a reflected change in pump speed, transmit an alert signal (e.g., toa system administrator), a system command (e.g., a command to increase apump speed of another pump in an attempt to compensate for a diminishedperformance of a stalled pump, a system-shut-down command, etc.), orboth.

In still another alternative embodiment, a leak detector circuit 225 canbe operatively coupled between the FG pin of the fan header 231 and thepump 210. In such an embodiment, the leak detector circuit 225 caninterrupt an FG signal emitted by the pump and convey an alternative FGsignal (or no FG signal) to the FG signal pin in response to a detectedleak. The alternative FG signal can simulate a diminished pump speed, aselected increased pump speed, or no pump speed. A system configured tomonitor the simulated FG signal can, in response to a selected change inthe simulated FG signal corresponding to a change in pump speed,transmit an alert signal (e.g., to a system administrator), a systemcommand (e.g., a command to increase a pump speed of another pump in anattempt to compensate for a diminished performance of a stalled pump, asystem-shut-down command, etc.), or both.

A leak sensor 225 can be positioned adjacent to (e.g., routed around) apump 210 or other component of a liquid-based heat-transfer system, asindicated by way of example in FIGS. 8 and 9. For example, a sensor 225can be positioned on, embedded in, affixed to, positioned adjacent to,or otherwise operatively coupled to a printed circuit board 205 suchthat the sensor defines a sensor region 226. The sensor region can beselected to correspond to a region that might be susceptible to wettingby a working fluid in the event of a leak.

FIGS. 8 and 9 show examples of a sensitive region defined by a leaksensor 225. The illustrated sensitive region 226 extends along the leaksensor (e.g., between points “A” and “B”) routed on a surface of aprinted circuit board 205. With circuits configured as shown in FIG. 8,the leak detector can be configured to interrupt a tachometer signalemitted by each pump 210 in response to a detected leak. Alternatively,each of the illustrated pumps 210 and the leak detector circuit 225 canbe configured to emit one or more simulated fan-tachometer signalscorresponding to one or more respective observed operational states. Theone or more simulated fan-tachometer signals can be transmitted over theillustrated fan headers 231, for example, to an IPMI bus. A controllercan receive and interpret the one or more signals as a proxy for theobserved operational state, and responsively issue one or morecorresponding system commands.

In FIG. 9, the leak detector circuit 225′ is configured to interrupt asimulated tachometer signal in response to a detected leak. Suchinterruptions can simulate a tachometer signal emitted by a fan having a“locked rotor.” A corresponding control system configured to monitor atachometer signal emitted from a fan can respond to a simulated “lockedrotor” signal by initiating an alert or other system command.

Overview of Flow Sensors

FIG. 10 illustrates a fluid circuit 310 having a pump 320, an opticalflow-rate sensor 330, a heat exchanger 340 configured to transfer heat341 from a heat dissipating component (e.g., a microprocessor), and aradiator 350 configured to dissipate heat 351 from the working fluid toan environment 352. In some fluid circuits, the pump 320 and the heatexchanger 340 are combined into an operative subassembly, as describedby way of example in U.S. patent application Ser. No. 12/189,476, amongother patent applications.

A flow-rate sensor 330 can include a rotational member 332 positionedwithin a segment of conduit 331 and a tachometer 334 configured todetect a rotational speed of the rotational member. As shownschematically in FIG. 11, the rotational member 332 can be configured toreceive momentum from a flow of a working fluid passing over therotational member, in a manner similar as a turbine of a windmillreceiving momentum from a flow of air passing over the turbine. Arotational member 332 of the type disclosed herein can include agenerally axisymmetric arrangement of wings, foils, blades, faces, orscrews positioned within a conduit suitable for conveying a flow of aworking fluid such that a flow of a selected fluid passing over thearrangement of wings, foils, blades, faces, or screws applies atorsional force to the rotational member to urge the rotational memberin rotation about the axis of rotation.

Some body portions comprise a thin shell member having opposed first andsecond sides 337 a, 337 b. As shown in FIG. 13, a thin shell member candefine a primary axis 338 extending longitudinally of the shell memberand a secondary axis 338 a extending transversely relative to theprimary axis. The thin shell member can be twisted about the primaryaxis 338 so as to define a foil-shaped member configured to convertmomentum from a passing fluid to a torsional force applied to the thinshell member. FIG. 13 shows but one possible example of such afoil-shaped member.

A torsional force applied to the rotational member (e.g., member 332)can correspond to a rate of flow of a working fluid past the rotationalmember, with higher flow rates corresponding to relatively highertorsional forces. For example, a lift force on a wing in a stream of anincompressible fluid can increase in proportion to the square of thespeed of the approaching fluid. A lift force applied to the rotationalmember 332 at a position spaced apart from a central, longitudinal axis338 applies a turning moment (e.g., a torque, or a torsional force) tothe rotational member about the axis 338. The turning moment can urgethe rotational member 32 in rotation. In some axisymmetric embodimentsof rotational members 332, the turning moment can urge the rotationalmember 332 in rotation about the central, longitudinal axis 338. Theturning moment can correspond to the lift force (torsional force)generated by the flow of the working fluid past the rotational member.Moreover, the speed of rotation of the rotational member 332 cancorrespond to the torsional force applied to the rotational member.Accordingly, the rotational speed of the rotational member cancorrespond to the speed of an approaching flow of the fluid. And, avolumetric flow rate (or a mass flow rate) of the fluid through a closedconduit corresponds to the speed of the fluid through the conduit.

Thus, a rotational speed of the rotational member 332 positioned withina fluid conduit can correspond to a volumetric flow rate (or mass flowrate) of a fluid through the conduit 331. Although determining analgebraic expression for a relationship between rotational speed of agiven rotational member in a flow of a selected fluid might be possible,such a relationship or correlation can be determined experimentally foreach combination of rotational member configuration, conduitconfiguration, and working fluid.

Though not to scale, the plot in FIG. 15 generally illustrates oneexample of a correlation between an observed rotational speed of therotational member 332 and a (volumetric or mass) flow-rate past therotational member. An apparatus of the type shown in FIG. 14 can be usedto assess such a correlation and to generate such a plot.

For example, a conventional flow-rate sensor (e.g., a Venturi-typesensor) can be used to determine each of several selected (mass orvolumetric) flow rates of a working fluid, and the tachometer can emit asignal indicative of the rotational speed of the rotational member ateach respective flow rate. Each flow-rate/rotational speed pair ofreadings can be plotted as indicated by the plot shown in FIG. 15, toreveal an experimentally determined correlation between rotational speedof the rotational member 332 and fluid flow rate through the conduit,for a particular combination of rotational member configuration, conduitconfiguration, and working fluid. In general, a unique correlationbetween rotational speed of the rotational member and flow rate ofworking fluid exists for each combination of working fluid, rotationalmember configuration, and conduit configuration. However, once acorrelation between (volumetric or mass) flow rate and rotational speedis determined for a selected combination of conduit configuration,rotational member configuration, and working fluid, the rotational speedof the rotational member can be observed, and, based on the correlationof flow-rate through the conduit segment 332 and rotational speed of therotational member, the corresponding flow rate (e.g., volumetric or massflow rate) can be determined.

The tachometer can include any of a variety of known and hereafterdeveloped sensor arrangements suitable to detect a rotational speed ofthe rotational member 331. As but one example, a suitable tachometer caninclude an optical sensor having an emitter, a detector, and a counter.

For example, the rotational member 332 can be positioned in a conduit331 having a transparent outer wall 331 a, or other suitable portconfigured to permit a selected frequency range (or band) ofelectromagnetic radiation (e.g., radiofrequency, X-rays, or light in theinfrared, visible, or ultraviolet spectra) to pass therethrough.Although many suitable emitter and detector configurations are possible,the following discussion will refer to the emitter as a light emitterand the detector as a light detector by way of example, and notlimitation, for ease of description.

In some embodiments of flow sensors, a light emitter 333 can emit light(e.g., for a duration substantially longer than a period of rotation forthe rotational member 332) in a direction toward the rotational member332, and one or more portions 335 of the rotational member can reflectincident light (or other radiation band) from the emitter 333 toward thelight detector 336. The counter 337 can increment a count each time thelight detector 336 detects light reflected by the reflective portion 335of the rotational member 332. Such detection can be responsive to adetected presence of light compared to a detected absence of light, orto a detected absence of light compared to a detected presence of light.With such an arrangement, a rate at which the count increases (e.g., atime-rate-of-change of the count) can correspond to a rate at which thelight detector 336 detects a reflection of light from the rotationalmember 332. In turn, the rate at which the light detector 336 detects areflection of light from the rotational member 332 can correspond to arotational speed (i.e., a frequency of rotation, or an angular speed) ofthe rotational member 332, and thus, as noted above, a rate of flow of aworking fluid through a selected conduit.

For example, the rotational member 332 can be configured to reflectincident light toward the detector 336 once per revolution of therotational member about the axis of rotation, as with the member 332shown in FIGS. 13, 16A and 16B. As but one example, the rotationalmember 332 can have a relatively less reflective body portion 337 a, 337b that rotates about an axis of rotation 338 and a relatively morereflective reflector portion 335 affixed to or on, or integral with, therelatively less reflective body portion 337 a, 337 b. The reflectorportion 335 can be so arranged as to reflect light toward the detector336 once during each revolution of the body portion 332.

The reflector portion 335 can comprise a reflector member positioned onone of the opposed sides 337 a, 337 b of the thin shell member shown inFIGS. 13, 16A and 16B. With such an arrangement, a rate (or a frequency)at which the count increments in response to detected reflections fromthe reflector portion 335 can approximate the angular speed of therotational member, which in turn can correspond to a rate of flow of aworking fluid through the conduit 331.

As another example, the rotational member 332 can be configured toreflect incident light toward the detector 336 twice per revolution ofthe rotational member about the axis of rotation. For example, therotational member 332 can comprise opposed first and second reflectiveportions (not shown) so arranged relative to the opposed faces 337 a,337 b that each of the first and the second reflective portions reflectslight toward the detector 36 once during each revolution of therotational member (i.e., such that light is reflected toward thedetector 36 twice per revolution of the rotational member). With such anarrangement, one-half of a rate (or a frequency) at which the countincrements in response to detected reflections from the first and thesecond reflector portions can approximate the angular speed of therotational member, which in turn can correspond to a rate of flowthrough the conduit.

In general, the rotational member 332 can be configured to reflectincident light toward the detector N times per revolution of therotational member about the axis of rotation. With such an arrangement,1/N of a rate (or a frequency) at which the count increments in responseto detected reflections from the rotational member can approximate theangular speed of the rotational member, which in turn can correspond toa rate of flow through the conduit.

FIG. 12 shows a particular exemplary embodiment of a flow-rate sensor330 of the type described above. The illustrated sensor 330 has atransparent (in relation to a selected spectrum of incidentelectromagnetic radiation) segment 336 of conduit with a rotationalmember 332 positioned therein. A tachometer 334 is positioned externallyof the conduit and is arranged to emit light (or other band ofradiation) through the transparent segment 36 and toward the rotationalmember 332. The tachometer 334 is further arranged to detect light (orother radiation) reflected by the rotational member 332 through thetransparent segment 336.

The illustrated sensor 330 also has a retainer 360 configured to suspendthe rotational member 332 within the conduit 31 in spaced relation froman interior wall 331 b of the transparent segment of conduit. Such asuspended arrangement can permit the rotational member 332 to rotateabout a selected axis of rotation 338 within the conduit 331 and withoutbeing carried away by a flow of a working fluid passing through theconduit.

The retainer 360 can include an upstream retainer member 361 and adownstream retainer member 362. One or both of the retainer members 361,362 can be configured to urge outwardly against an inner wall 331 b ofthe segment 331 a of conduit. In some embodiments, one or both retainermembers 361, 362 comprise an elongate member that resiliently urgesagainst the wall 331 b, as shown in FIG. 12.

In some embodiments, one or both retainer members 361, 362 include asegment 363 configured to matingly engage with a correspondinglyconfigured region of the inner wall 331 b of the conduit 331 a. As FIG.12 shows, the segment 363 configured to matingly engage with the innerwall 331 b can include a bent segment 364 of wire configured to restwithin a corresponding détente 365, or other recessed region of theinner wall 331 b.

The rotational member 332 can be rotatably coupled to the retainer 360.For example, a first swivel member 366 a can rotatably couple therotational member 35 to an upstream retainer member 361 and a secondswivel member 366 b can rotatably couple the rotational member 335 to adownstream retainer member 362, as shown in FIG. 11.

The conduit 331 a having a rotational member 32 positioned therein canbe fluidly coupled in series (or “in-line”) with one or more othercomponents of a fluid circuit 310. Such a placement of the conduit 331 acan facilitate measurement of a rate of flow of a working fluid throughthe one or more components, once a correlation (e.g., FIG. 15) betweenobserved rotational speed of the rotational member 332 and a volumetric(or mass) flow rate of the working fluid through the conduit 331 a hasbeen determined.

A flow sensor 330 of the type described herein can be incorporated in acooling system, such as, for example, a cooling system configured tocool an electronic component or other device that dissipates waste heatduring operation. As noted above, a tachometer output of such a flowsensor can indicate a rate of fluid flow through the sensor.

In some embodiments, the output of the tachometer 334 can be multiplexedso as to be compatible with a known or installed communication bus,e.g., over an IPMI bus. As noted above, a computer system incorporatinga cooling system can include a controller configured to transmit analert or other command in response to an observed signal exceeding aselected upper threshold or falling below a selected lower threshold.The observed signal can be emitted by a flow sensor. In some instances,the emitted signal can be emitted by a tachometer 334 configured toobserve a rotational speed of a rotational member 332, and the controlsystem can transmit an alert or other command in response to an observedtachometer signal exceeding a selected upper threshold or falling belowa selected lower threshold. The upper or lower threshold can correspondto an upper or a lower fluid flow-rate threshold.

As well, or alternatively, a flow-rate sensor, e.g., an opticalflow-rate sensor 330 of the type described herein, can emit a simulatedfan-tachometer signal in correspondence with an observed flow rate (orindicia thereof). For example, until a lower threshold flow rate (orindicia thereof) is observed by the flow-rate sensor, the sensor canemit a simulated fan-tachometer signal indicative of a given conditionof a fan, for example, a stalled fan rotor. Between the lower thresholdflow rate (or indicia thereof) and a selected upper threshold observedflow rate (or indicia thereof), the sensor can emit a correspondingsimulated fan-tachometer signal indicative of a selected fan speed. Asbut one example, a correlation can be defined between simulatedfan-tachometer speed and observed flow rate (or indicia thereof) betweenselected upper and lower threshold flow rates (or indicia thereof), asshown in FIG. 17. With such a pre-defined correlation, the sensor 330can emit a simulated fan-tachometer signal correlated to (or encoding) aflow rate (or indicia thereof) observed by the sensor. The simulatedfan-tachometer signal can be conveyed over a known bus using knownprotocols (e.g., an IPMI bus) and observed by a control system. Thecontrol system, in turn, can decode the simulated fan-tachometer signalusing the known correlation (FIG. 17) between observed flow rate (orindicia thereof) and simulated fan speed.

Some flow-rate sensors can have an electrical circuit operativelycoupled to an FG signal pin of a header and be configured to emit asimulated tachometer signal having a waveform similar to a waveformemitted by an operating (or stalled) fan. The electrical circuit (notshown) can be further configured to emit a simulated tachometer signalhaving a waveform similar to a failed or failing fan in response to anobserved flow rate (or indicia thereof) below a selected lowerthreshold.

A flow-rate sensor can be operatively coupled to a control systemassociated with one or more pumps of the liquid-based heat-transfersystem. The control system can emit a control signal for adjustingoperation of one or more pumps in the fluid circuit (e.g., a coolingsystem) responsively to an observed proxy (or other) signal emitted by aflow-rate sensor.

For example, if the signal emitted by the flow-rate sensor indicates alower-than-desired flow rate (e.g., based on an observed systemworkload, such as a microprocessor workload, or read/write trafficacross a memory bus), the control system can emit a control signal. Sucha control signal can cause a given one or more pump to increase speed,can cause a supplemental pump to become operational, and/or can cause avalve to open (or close), to increase flow rate through a desiredportion of a cooling system. Such a control signal can alter anoperational state of a computer system. For example, if additionalsystem cooling is unavailable by increasing pump speed, opening a valve,or operating a supplemental pump, the computer system can reduce orlimit workload of a subsystem at risk of overheating (e.g.,microprocessor workload can be limited or reduced, read/write trafficacross a memory bus can be limited or reduced) absent increased cooling.

As another example, if the signal emitted by the flow-rate sensorindicates a higher-than-necessary flow rate (e.g., based on an observedsystem workload, such as a microprocessor workload, or read/writetraffic across a memory bus), the control system can emit a controlsignal. Such a control signal can cause a given one or more pumps todecrease speed (e.g., to save power and/or lower acoustic emissions bythe pump), cause a supplemental pump to slow down or to stop operating,and/or cause a valve to open (or close), decreasing flow rate through aportion of a cooling system to a suitable level.

Other Multiplexed Proxies

As one generalized example, a sensor circuit can be configured to emit aproxy signal corresponding to an observed operational state. Each in aplurality of discrete proxy signals can correspond to each respectiveobserved operational state in a plurality of observable operationalstates.

In some instances, such a proxy signal can be a simulated fan-tachometersignal. Each discrete simulated fan-tachometer signal can correspond toa respective observed operational state. For example, a simulatedfan-tachometer signal corresponding to a fan speed of 200 RPM canconstitute a proxy for a selected observed flow rate (or indiciathereof, such as, for example, a rate of increasing count of detectedreflections from a reflective portion 35 of a rotational member 32).With such an example, a simulated fan-tachometer signal corresponding toa different fan speed (e.g., 250 RPM) can constitute a proxy for another(e.g., higher) observed flow rate (or indicia thereof) within the system10.

As another example, a simulated fan-tachometer signal corresponding to afan speed of 200 RPM can constitute a proxy for an observed first flowrate at a location within the system and a simulated fan-tachometersignal corresponding to a fan speed of 250 RPM can constitute a proxyfor an observed second (e.g., different) flow rate. FIG. 17 shows anexample, pre-defined correlation between simulated fan-tachometer signaland flow rate.

In some instances, a simulated fan-tachometer signal corresponding to afan speed of 200 RPM can constitute a proxy for an observed leak at afirst location within the system and a simulated fan-tachometer signalcorresponding to a fan speed of 250 RPM can constitute a proxy for anobserved leak at a second (e.g., different) location within the system.

Such proxy signals can be transmitted over and observed from, forexample, the IPMI bus. A controller operatively coupled to the IPMI buscan observe the proxy signal, interpret the observed proxy signal, as bycomparison to a lookup table, and, if appropriate, issue one or moreselected system commands responsively to the observed or interpretedproxy signal.

By way of illustrate of disclosed principles, the following tablesummarizes specific examples of proxy signals, proxy signal values andcorresponding operational states represented by the proxy signal values:

PROXY CORRESPONDING PROXY SIGNAL SIGNAL VALUE OPERATIONAL STATEsimulated 200 rpm Leak at position “A” in system fan-tachometer 250 rpmleak at position “B” in system signal 300 RPM Pump 1 failure 350 RPMPump 1 operating normally 400 RPM Pump 2 failure 450 RPM Pump 2operating normally 500 RPM Observed temperature (e.g., temperature ofelectronic component, pump motor, liquid coolant or air) over selectedthreshold or within a predefined range 550 RPM Observed temperature(e.g., temperature of electronic component, pump motor, liquid coolantor air) over another selected threshold or within a different predefinedrange

Computing Environments

FIG. 18 illustrates a generalized example of a suitable computingenvironment 400 in which described methods, embodiments, techniques, andtechnologies relating, for example, to detection and/or removal ofunwanted noise signals from an observed signal can be implemented. Thecomputing environment 1100 is not intended to suggest any limitation asto scope of use or functionality of the technologies disclosed herein,as each technology may be implemented in diverse general-purpose orspecial-purpose computing environments. For example, each disclosedtechnology may be implemented with other computer system configurations,including wearable and handheld devices (e.g., a mobile-communicationsdevice, or, more particularly but not exclusively, IPHONE®/IPAD®devices, available from Apple Inc. of Cupertino, Calif.), multiprocessorsystems, microprocessor-based or programmable consumer electronics,embedded platforms, network computers, minicomputers, mainframecomputers, smartphones, tablet computers, data centers, and the like.Each disclosed technology may also be practiced in distributed computingenvironments where tasks are performed by remote processing devices thatare linked through a communications connection or network. In adistributed computing environment, program modules may be located inboth local and remote memory storage devices.

The computing environment 1100 includes at least one central processingunit 1110 and memory 1120. In FIG. 18, this most basic configuration1130 is included within a dashed line. The central processing unit 1110executes computer-executable instructions and may be a real or a virtualprocessor. In a multi-processing system, multiple processing unitsexecute computer-executable instructions to increase processing powerand as such, multiple processors can run simultaneously. The memory 1120may be volatile memory (e.g., registers, cache, RAM), non-volatilememory (e.g., ROM, EEPROM, flash memory, etc.), or some combination ofthe two. The memory 1120 stores software 1180 a that can, for example,implement one or more of the innovative technologies described herein,when executed by a processor.

A computing environment may have additional features. For example, thecomputing environment 1100 includes storage 1140, one or more inputdevices 1150, one or more output devices 1160, and one or morecommunication connections 1170. An interconnection mechanism (not shown)such as a bus, a controller, or a network, interconnects the componentsof the computing environment 1100. Typically, operating system software(not shown) provides an operating environment for other softwareexecuting in the computing environment 1100, and coordinates activitiesof the components of the computing environment 1100.

The store 1140 may be removable or non-removable, and can includeselected forms of machine-readable media. In general, machine-readablemedia includes magnetic disks, magnetic tapes or cassettes, non-volatilesolid-state memory, CD-ROMs, CD-RWs, DVDs, magnetic tape, optical datastorage devices, and carrier waves, or any other machine-readable mediumwhich can be used to store information and which can be accessed withinthe computing environment 1100. The storage 1140 stores instructions forthe software 1180 b, which can implement technologies described herein.

The store 1140 can also be distributed over a network so that softwareinstructions are stored and executed in a distributed fashion. In otherembodiments, some of these operations might be performed by specifichardware components that contain hardwired logic. Those operations mightalternatively be performed by any combination of programmed dataprocessing components and fixed hardwired circuit components.

The input device(s) 1150 may be a touch input device, such as akeyboard, keypad, mouse, pen, touchscreen, touch pad, or trackball, avoice input device, a scanning device, or another device, that providesinput to the computing environment 1100. For audio, the input device(s)1150 may include a microphone or other transducer (e.g., a sound card orsimilar device that accepts audio input in analog or digital form), or acomputer-readable media reader that provides audio samples to thecomputing environment 1100.

The output device(s) 1160 may be a display, printer, speaker transducer,DVD-writer, or another device that provides output from the computingenvironment 1100.

The communication connection(s) 1170 enable communication over acommunication medium (e.g., a connecting network) to another computingentity. The communication medium conveys information such ascomputer-executable instructions, compressed graphics information,processed signal information (including processed audio signals), orother data in a modulated data signal.

Thus, disclosed computing environments are suitable for transforming asignal corrected as disclosed herein into a human-perceivable form. Aswell, or alternatively, disclosed computing environments are suitablefor transforming a signal corrected as disclosed herein into a modulatedsignal and conveying the modulated signal over a communicationconnection

Machine-readable media are any available media that can be accessedwithin a computing environment 1100. By way of example, and notlimitation, with the computing environment 1100, machine-readable mediainclude memory 1120, storage 1140, communication media (not shown), andcombinations of any of the above. Tangible machine-readable (orcomputer-readable) media exclude transitory signals.

Couplers

FIG. 19 shows a photograph of one embodiment of a two-member coupler.The fluid coupler 400 has a first member 410 configured to matinglycouple with and to decouple from a second member 420 to provide adecoupleable coupling between a corresponding first fluid conduit 401and a corresponding second fluid conduit 402. Such a coupling isdepicted, for example, schematically at inlets 150 a-n and outlets 140a-n in FIG. 6 in U.S. patent application Ser. No. 13/559,340. To inhibita leak of fluid from the coupler 400 when coupling or decoupling thefirst and the second members 410, 420 to or from each other, one or bothof the members 410, 420 can have an internal valve that automaticallycloses before, during or after the members 410,420 are decoupled fromeach other and automatically opens before, during or after the membersare coupled to each other.

For example, a first member 410 can define an open interior bore 413sized to receive a shank 422 extending from the second member 420.Either or both members 410, 420 can define an interior valve that opensafter the bore 413 matingly and/or sealingly engages the shank 422. Forexample, an interior wall of the bore 413 can have a pliable gasket(e.g., an O-ring) extending circumferentially around the bore andpositioned at a selected first depth within the bore. The gasket can beconfigured relative to the shank (e.g., a diameter thereof) to sealinglyengage with an outer surface of the shank 422 as the shank slides intothe bore 413 to a depth greater than the selected first depth. As theshank slides deeper into the bore, a portion within the bore 413 canurge against a portion of the shank to open either or both valvescorresponding to the respective members 410, 420 and thereby tofluidically couple the first conduit 401 with the second conduit 402.

Such automatic actuation of the valves can result from a resilientlycompressible member (e.g., a spring, not shown). For example, the valvecan be closed in an “at-rest” position when urged by a correspondingresiliently compressible member. The coupling members 410, 420 candefine correspondingly configured features that urge the valve openagainst the force applied by the resiliently compressible member as themembers 410, 420 are brought into a mating engagement. With such anautomatically actuatable valve, the coupler members 410, 420 can inhibitfluid leaks when coupling or decoupling the coupler members 410, 420.

As well, a compressive force applied between the members 410, 420 thatactuates the valve by overcoming a force of a resilient member, as justdescribed, can compress such a resilient member. The compressedresilient member can urge the members 410, 420 apart from each otherwhen the compressive force is removed.

However, the coupler 400 can also have a retainer configured to retainthe decoupleable coupling between the first member 410 and the secondmember 420 against the outwardly applied force of the compressedresilient member. However, when a retention force applied by theretainer to the first and the second members 410, 420, the compressedresilient member can urge the first member 410 and the second member 420apart with sufficient force as to cause the coupled members 410, 420 todecouple from each other and thereby to automatically close therespective valves.

The retainer depicted in FIG. 19 includes a cylindrical sleeve 414overlying a body 412 of the first member 410, a plurality of bearingspositioned at discrete circumferential positions relative to the bore413, as well as a groove 424 positioned proximally of the shank 422 ofthe second member 420. When the first and the second members 410, 420are matingly engaged with each other, the bearings 418 rest within thegroove 424. The wall of the groove urges against the bearings when themated first and the second members 410, 420 are urged together incompression or pulled apart in tension, and the sleeve 414 overlying thebearings prevents the bearings 418 from moving radially outward from thebore 413, locking the first and the second members 41, 420 together.

The sleeve 414 can slide longitudinally to and fro relative to the body412 from a retention configuration, as shown in FIG. 19 to anengagement/disengagement configuration (not shown). In theengagement/disengagement configuration, the sleeve 414 longitudinallyretracts from the depicted retention configuration until the sleeveurges against a shoulder 416 defined by the body 412. When the sleeve414 is retracted, the bearings 418 can move radially outward relative tothe bore 413, allowing the members 410, 420 to separate from each otheras they are pulled apart.

The illustrated sleeve defines an outer surface and a circumferentiallyextending groove recessed from the outer surface. The groove facilitatesgripping by a user's hand when retracting the sleeve 414 relative to thebody 412. As well, the coupler member 410 includes a resilient member(e.g., a spring, not shown) configured to resiliently urge the sleeve414 toward the retention configuration shown in FIG. 19. To retract thesleeve to the engagement/disengagement configuration, the force of theresilient spring and any friction as between the sleeve and the body 412needs to be overcome. Once the sleeve is partially or fully retractedfrom the illustrated retention configuration, the resilient member urgesthe sleeve 414 toward the retention configuration. In many embodiments,the force applied to the sleeve by the resilient member sufficientlyexceeds any frictional force between the sleeve 414 and the body 412 toallow the sleeve 414 to automatically return to the illustratedretention configuration. As described more fully below, the forceapplied to the sleeve 414 by the resilient member sufficiently exceedssuch frictional forces as well as other forces, e.g., servo or otheractuator resistance when the servo or other actuator is not actuated.The working embodiment shown in FIG. 20 includes automaticallydecoupleable couplers similar in arrangement to the coupler 400 shown inFIG. 19 and described above.

The cooling system shown in FIG. 20 is similar to a cooling systemdisclosed, for example, in U.S. patent application Ser. No. 13/559,340,filed Jul. 26, 2012, and the applications from which the '340Application claims priority, each of which patent applications is herebyincorporated by reference as if recited in full herein. For example,referring to FIG. 20, the distribution manifold 401 b has severalcoupler members 410 b configured to couple with corresponding couplermembers 420 b affixed to an inlet conduit 402 b. At an end of theconduit 402 b positioned opposite the coupler member 420 b, the conduitis coupled to a cold plate to deliver coolant to the cold plate from thedistribution manifold 410 b. Similarly, the collection manifold 401 ahas several coupler members 410 a configured to couple withcorresponding coupler members 420 a affixed to an outlet conduit 402 a.At an end of the conduit 402 a positioned opposite the coupler member410 a, the conduit 402 a is coupled to a corresponding cold plate toreceive heated coolant from the respective cold plate. The workingembodiment has first and second cold plates, and the conduit 402 b iscoupled to the first cold plate and the conduit 402 a is coupled to thesecond cold plate. In other embodiments, however, the conduits 402 a,402 b are coupled to the same cold plate. Still other embodiments havemore than two cold plates and the conduits 402 a, 402 b are coupled torespective cold plates and the remaining cold plates are coupled to therespective cold plates fluidically between the conduits 402 a, 402 b.

The working embodiment also includes an actuator shaft 430 mechanicallycoupled with the sleeves 414 of the coupler members 410 a, 410 b. Suchmechanical coupling can be any form of coupling or linkage sufficient topermit the actuator shaft 430 to longitudinally slide the sleeves 414 toretract the sleeves from overlying the bearings and thereby to permitthe coupler members 410 a, 410 b to decouple from each other.

As the white double-headed arrow indicates, the actuator shaft 430 canlinearly translate generally perpendicularly to the manifolds 401 a, 401b and generally parallel to a longitudinal axis of the coupler members410 a, 410 b. As the actuator shaft 430 retracts toward the manifolds401 a, 401 b with a force sufficient to overcome friction between thesleeves 414 and the corresponding bodies 412, as well as the forceapplied by the resilient member, the sleeves 414 of the respectivecoupler members 410 a, 410 b also retract, permitting the bearings 418(FIG. 19) to move radially outward of the bore 413 (FIG. 19) and theshank 422 to eject from the bore, as shown in FIG. 20. In someembodiments, including in the working embodiment, the coupler members410 a, 410 b separate automatically under the force of the resilientmember that urges the valves closed when the retainer sleeve 414retracts sufficiently to permit the bearings to move radially outward.In FIG. 20, the actuator shaft 430 has returned to an unactuated,extended position in which the sleeves 414 overlie the bearings 418,after the shaft 430 retracted the sleeves 414 to automatically eject thecoupler members 420 a, 420 b.

In the embodiment shown in FIG. 20, the actuator shaft is mechanicallycoupled to two sleeves 414. In other embodiments, each activator shaftcan be coupled to only one sleeve or more than two sleeves. For example,some servers can have more than one inlet conduit 402 b and/or more thanone outlet conduit 402 a, and one actuator shaft can be configured toretract each sleeve 414 corresponding to all inlet and outlet conduitsfor a give server. In still other embodiments, one actuator shaft 430 ismechanically coupled to each of one or more inlet conduits for a givenserver and another actuator shaft is mechanically coupled to each of oneor more outlet conduits for the given server.

A servo, a stepper-motor, or other electro-mechanical actuator (notshown) can urge the actuator shaft 430 or other linkage to translate inspace from a first position to a second position. The first position cancorrespond to a retention configuration of a coupler of the typedescribed herein and the second position can correspond to anengagement/disengagement configuration of the coupler (e.g., with thesleeve 414 retracted toward the shoulder 416). The servo or otheractuator can be activated by a controller responsively to a change in anobserved state of an operational parameter. For example, a controllercan activate the servo or other actuator responsively to an alert orother command issued by a control system, or (e.g., with a latchingcontrol system) responsively to an absence of an alert or other command.

As but one example, the conduits 402 a, 402 b corresponding to a coolingsystem for a given server can be automatically disconnected from themanifolds 401 a, 401 b in response to a leak being detected within thegiven server, while all other servers in the rack can remainoperational. For example, each server can have one or more correspondingleak sensors, e.g., of the type described herein, and each leak sensorcan have a unique identifier (e.g., address). In some instances,including the working embodiment, the leak sensor is configured as arepositionable cable that can be positioned within a given server at oneor more selected positions reasonably calculated by a user to be exposedto a cooling-system leak. Each leak sensor can be coupled to acontroller configured to interpret an output signal from the leak (orother) sensor. The controller can have a look up table or otherreference for establishing correspondence between each of several leak(or other) sensors and the server in or on which each leak sensor ispositioned.

As well, each actuator shaft 430 (or corresponding actuator) can have aunique identifier, and another look up table or other reference canestablish correspondence between each of several actuators and one ormore servers. Accordingly, when the control system detects a leak (orother change of state) in a given server, the control system canidentify the given server (or location in a given server), issue analert identifying which one or more selected actuators should beactivated, e.g., to automatically decouple the conduits 402 a, 402 bfrom the manifolds 401 a, 401 b to prevent further leaking within theaffected server. The controller can further activate the one or moreidentified actuators and thereby urge the actuator shaft 430 (or otheractuator member) through a range of motion contemplated to remove aretention force applied to the coupling 400, as by retracting thesleeves 414. Other detected changes of state can also actuate anactuator, e.g., to allow an automatic disconnection from the manifolds.Such a change in state can include, for example, a detected coolanttemperature above or below a selected threshold temperature, a detectedpower failure, an observed pressure exceeding an upper thresholdpressure, etc.

In the working embodiment depicted in FIG. 20, the actuator shaft 430extends from a two-position linear actuator. The linear actuator (notshown) retracts when supplied with power and thereby urges the sleeves414 toward the engagement/disengagement configuration when activated.When not activated, the linear actuator applies little or nolongitudinal load to the sleeves, allowing the sleeves to resilientlyreturn to the retention configuration (e.g., as under forces applied bysprings within the first member 410 (FIG. 19) configured to urge thesleeve 414 toward the retention configuration shown in FIG. 19. In otherembodiments, the linear actuator can urge the actuator shaft 430 awayfrom the actuator when supplied with power.

Referring again to FIG. 6 in U.S. patent application Ser. No.13/559,340, an actuator as just described can be operably coupled to,for example, the inlet couplers 150 a-n and/or the outlet couplers 140a-n. One or more leak detectors, flow rate sensors, and/or other sensorscan be suitably arranged relative to each heat-transfer element 110 a-nand corresponding operable devices that might be damaged from, forexample, exposure to a leaked coolant or other working fluid. Acontroller as described herein can issue an alarm or a command to whichthe actuator can respond by urging, for example, the respective sleeves414 toward the engagement/disengagement configuration. When the sleeveis sufficiently retracted, the compressive force applied to aninternally positioned resilient member can be removed, causing thematingly engaged members 410, 420 to urge apart from each other as theresilient member returns to an uncompressed arrangement. An internalvalve in each respective member 410, 420 can close to prevent leakage ofa working fluid from the flow passages corresponding to the members 410,420, thereby isolating the respective heat-transfer element(s) 110 a-nfrom the remainder of the fluid circuit positioned among the variousservers. Once a given branch of a heat-transfer system's fluid circuithas been isolated as just described, the corresponding equipment can beremoved, inspected, and repaired without disrupting operation ofadjacent equipment.

Any actuator suitable to retract one or more sleeves 414 can be used.Examples of suitable actuators include linear motors, linear servos,ball-screws coupled with a rotary motor or servo, four-bar linkages,among other types of linear actuators configured to urge the actuatorshaft 430 through a range of motion sufficient to retract one or moresleeves 414.

Other arrangements of actuators and couplers are possible. For example,the couplers described thus far are coupleable and decoupleable bysliding the sleeve 414 in a longitudinal direction. However, somecouplers are configured to decouple only after a member (e.g., a sleeve)rotates through a selected angle. In such an embodiment, a rotationalactuator, stepper motor, or servo can be coupled to the rotatable memberto automatically decouple the coupler. In still other embodiments, thecoupler can require a combination of linear and rotational movement toautomatically decouple the coupler. In such an embodiment, atwo-degree-of-freedom actuator (e.g., an actuator or combination ofactuators configured to urge a member in rotation and in lineartranslation) can be coupled to the coupler to automatically decouple thecoupler.

Other apparatus and methods for isolating one or more branches of afluid circuit of a heat-transfer system are possible. For example,referring to FIG. 21, a proportional or a zero-flow valve 502 can bepositioned adjacent an inlet 150 a to a branch (e.g., a heat-transferelement 110) of a fluid circuit in a heat-transfer system, and a checkvalve 501 can be positioned adjacent a corresponding outlet 140 a. Anactuator 503 of the type described herein can be operably coupled withthe valve 502, as shown schematically in FIG. 21, and can cause thevalve to open or close, entirely or partially, in response to an alarmor a command issued by a controller. On closing the valve 502, the checkvalve 501 can close to prevent a reversed flow (sometimes referred to inthe art as “backflow”) of working fluid through the outlet 140 a. Theclosure of the valves 501, 502 isolate the branch (e.g., theheat-transfer element 110 a in FIGS. 1, 2, 3, 5, and 6 of U.S. patentapplication Ser. No. 13/559,340) from the remainder of the heat-transfersystem.

For conciseness and clarity, the foregoing describes isolation of abranch 110 a of a heat-transfer system passing within a given server.Nonetheless, apparatus and methods just described can be suitable forisolating other branches of heat-transfer systems. For example, U.S.patent application Ser. No. 13/559,340 describes removing heat from arack containing a plurality of servers by passing a facility coolantthrough a liquid-liquid heat exchanger. Depending on the plumbingarrangement of a given facility, a facility's coolant circuit can have aplurality of branches coupled to each other, for example, in parallelrelative to a main conduit, similar to the arrangement of the pluralheat-transfer elements 110 a-n relative to each other and the manifoldmodule 200 in FIGS. 5 and 6 in U.S. patent application Ser. No.13/559,340. One or more such branches of a facility's coolant circuitcan have a zero-flow or a proportional valve adjacent an inlet and acheck valve positioned adjacent an outlet, and an electro-mechanicalactuator can be operatively coupled to such zero-flow or proportionalvalve. The electro-mechanical actuator can be activated responsively toan alert or other command to close the corresponding valve, therebyisolating the corresponding branch from the facility's coolant circuit.

Other Exemplary Embodiments

The examples described herein generally concern control systems, withspecific examples of control systems being configured to respond to adetected condition or operational state of a liquid-based heat-transfersystem, e.g., to issue an alert or other command responsive to adetected leak of a working fluid or to issue an alert or other commandresponsive to an observed flow rate of a working fluid. Other aspectsare described, as well. For example, electro-mechanical actuatorsarranged to isolate one or more corresponding branches of a fluidcircuit are described. As but one other example, a pump speed can beadjusted responsive to a signal emitted by a flow-rate sensor. Thesignal can be indicative of an observed flow rate of working fluid (oran indicia thereof, by way of example, a rotational speed of arotational member within a segment of conduit). Other embodiments ofleak detectors, flow-rate sensors, flow-path isolators, methods,circuits and/or control systems than those described above in detail arecontemplated based on the principles disclosed herein, together with anyattendant changes in configurations of the respective apparatus and/orcircuits described herein. Incorporating the principles disclosedherein, it is possible to provide a wide variety of control systemsconfigured to issue an alert or other command, and/or, based on adetected change in state or operation (e.g., a detected leak or changein observed flow rate), to adjust an operation of a wide variety ofsystems, including by way of example, a heat-transfer system for any ofa data center, a laser component, a light-emitting diode, a chemicalreactor, photovoltaic cells, solar collectors, and a variety of otherindustrial, military and consumer devices now known and hereafterdeveloped. Moreover, systems disclosed above can be used in combinationwith other liquid-based systems including, inter alia, reactor vessels.

Although the discussion of couplers presented herein pertains to fluidcouplers, those of ordinary skill in the art will appreciate following areview of this disclosure that the innovative principles disclosed inrelation to fluid couplers can be readily applied to other forms ofcouplers, including electrical couplers, pneumatic couplers, opticalcouplers, etc.

Directions and references (e.g., up, down, top, bottom, left, right,rearward, forward, etc.) may be used to facilitate discussion of thedrawings and principles herein, but are not intended to be limiting. Forexample, certain terms may be used such as “up,” “down,”, “upper,”“lower,” “horizontal,” “vertical,” “left,” “right,” and the like. Suchterms are used, where applicable, to provide some clarity of descriptionwhen dealing with relative relationships, particularly with respect tothe illustrated embodiments. Such terms are not, however, intended toimply absolute relationships, positions, and/or orientations. Forexample, with respect to an object, an “upper” surface can become a“lower” surface simply by turning the object over. Nevertheless, it isstill the same surface and the object remains the same. As used herein,“and/or” means “and” or “or”, as well as “and” and “or.” Moreover, allpatent and non-patent literature cited herein is hereby incorporated byreferences in its entirety for all purposes.

The principles described above in connection with any particular examplecan be combined with the principles described in connection with any oneor more of the other examples. Accordingly, this detailed descriptionshall not be construed in a limiting sense, and following a review ofthis disclosure, those of ordinary skill in the art will appreciate thewide variety of fluid heat exchange systems that can be devised usingthe various concepts described herein. Moreover, those of ordinary skillin the art will appreciate that the exemplary embodiments disclosedherein can be adapted to various configurations without departing fromthe disclosed principles.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedinnovations. Those of ordinary skill in the art will appreciate that theexemplary embodiments disclosed herein can be adapted to variousconfigurations and/or uses without departing from the disclosedprinciples. For example, the principles described above in connectionwith any particular example can be combined with the principlesdescribed in connection with another example described herein. Variousmodifications to those embodiments will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other embodiments without departing from the spirit or scopeof this disclosure. Accordingly, this detailed description shall not beconstrued in a limiting sense, and following a review of thisdisclosure, those of ordinary skill in the art will appreciate the widevariety of filtering and computational techniques can be devised usingthe various concepts described herein.

Similarly, the presently claimed inventions are not intended to belimited to the embodiments shown herein, but are to be accorded the fullscope consistent with the language of the claims, wherein reference toan element in the singular, such as by use of the article “a” or “an” isnot intended to mean “one and only one” unless specifically so stated,but rather “one or more”. All structural and functional equivalents tothe elements of the various embodiments described throughout thedisclosure that are known or later come to be known to those of ordinaryskill in the art are intended to be encompassed by the featuresdescribed and claimed herein. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. No claim element is tobe construed under the provisions of 35 USC 112, sixth paragraph, unlessthe element is expressly recited using the phrase “means for” or “stepfor”.

Thus, in view of the many possible embodiments to which the disclosedprinciples can be applied, we reserve the right to claim any and allcombinations of features described herein, including the right to claimall that comes within the scope and spirit of the foregoing description,as well as the combinations recited in the claims below and presentedanytime throughout prosecution of this application, literally andequivalently.

We presently claim:
 1. A control system, comprising: a sensor circuitconfigured to emit a simulated signal corresponding to a selectedphysical parameter as a proxy for an observed operational parameterdifferent from the selected physical parameter; a controller configuredto receive the simulated signal and to infer from the simulated signal astate of the observed operational parameter; and an electro-mechanicalactuator selectively activatable based at least in part on the inferredstate of the observed operational parameter.
 2. A control systemaccording to claim 1, wherein the controller is further configured toemit a command signal responsive to the state of the observedoperational parameter and the electro-mechanical actuator is selectivelyactivatable responsively to the command signal.
 3. A control systemaccording to claim 1, wherein the simulated signal comprises a simulatedfan-tachometer signal, wherein the selected physical parameter comprisesa fan speed.
 4. A control system according to claim 3, wherein thesensor comprises a leak detector, and wherein the observed operationalparameter comprises a detected presence or a detected absence of a leakby the leak detector.
 5. A control system according to claim 1, whereinthe simulated signal comprises a simulated reproduction of a waveformemitted by a properly or an improperly operating, or a failed, fan.
 6. Acontrol system according to claim 1, wherein the selected physicalparameter comprises a rotational fan speed and the observed operationalparameter consists of one or more of an indicia of fluid level, anindicia of pressure, an indicia of electrical current, and an indicia ofa presence or absence of moisture.
 7. A control system according toclaim 1, wherein the observed operational parameter comprises an indiciaof a presence or absence of a working fluid externally of a liquid-basedheat-transfer system, wherein the sensor comprises an electrical circuitconfigured to emit the simulated signal responsive to the indicia of apresence of the working fluid externally of the liquid-based heattransfer system, and wherein the electro-mechanical actuator isconfigured to decouple matingly engaged couplers or to close a valve toisolate a branch of a fluid circuit.
 8. A method of isolating a branchof a fluid circuit from a liquid-based heat-transfer system, the methodcomprising: sensing a presence or an absence of a working fluidexternally of a liquid-based heat-transfer system; and activating anelectro-mechanical actuator to close a valve and/or to decouple matinglyengaged members of a fluid coupler.
 9. A method according to claim 8,further comprising emitting a signal responsive to the sensed presenceof the working fluid.
 10. A method according to 9, wherein a signalemitted in the sensed absence of the working fluid comprises a simulatedtachometer signal of the type emitted by an operable fan.
 11. Arack-mountable server system, comprising: a branch of a fluid circuitconfigured to convey a liquid from an inlet to the branch to an outletfrom the branch, wherein the inlet and the outlet are fluidly coupledwith a liquid supply and a liquid collector, respectively; a sensorconfigured to detect a presence of the working fluid externally of thebranch; and an electro-mechanical actuator configured to fluidly isolatethe branch from the fluid circuit responsive to a detected presence ofthe working fluid externally of the branch.
 12. A rack-mountable serversystem according to claim 11, further comprising: an electrical circuitoperatively coupled to the sensor and being configured to emit a signalresponsive to a detected presence of the liquid externally of theconduit, wherein the electro-mechanical actuator is actuatableresponsive to the signal.
 13. A rack-mountable server system accordingto claim 12, wherein the electro-mechanical actuator is configured toclose one or more valves and/or to decouple matingly engaged members ofa fluid coupling.
 14. A rack-mountable server system according to claim13, further comprising a linkage coupling the electromechanical actuatorto one or more of the valves and/or to a movable portion of the matinglyengaged members.
 15. A rack-mountable server system according to claim11, further comprising a server rack and a plurality of independentlyoperable servers received in the rack, wherein the liquid supplycomprises a distribution manifold and the liquid collector comprises acollection manifold, wherein the branch of the fluid circuit comprises abranch of a heat-transfer system corresponding to a first server andwherein the electro-mechanical actuator comprises a firstelectro-mechanical actuator corresponding to the first server, whereineach other server has a corresponding branch of the heat-transfer systemhaving an inlet fluidly coupled to the distribution manifold and anoutlet fluidly coupled to the collection manifold, and a correspondingelectro-mechanical actuator configured to fluidly isolate the respectivebranch from the heat-transfer system.
 16. A rack-mountable server systemaccording to claim 15, wherein the inlet to each branch of theheat-transfer system comprises a first member of a decoupleable fluidcoupling and wherein the distribution manifold comprises a correspondingsecond member of the decoupleable fluid coupling, wherein eachrespective first member and corresponding second member are socorrespondingly configured as to be matingly engageable with each other,wherein the respective electro-mechanical actuator is configured todecouple the respective matingly engaged first member and second memberfrom each other.
 17. A rack-mountable server system according to claim15, further comprising a plurality of valves, wherein each valve ispositioned adjacent a corresponding one of the branch inlets, whereineach valve is selectively activatable by the correspondingelectro-mechanical actuator.
 18. A rack-mountable server systemaccording to claim 17, further comprising a plurality of check valves,wherein each check valve is positioned adjacent a corresponding one ofthe branch outlets and configured to prevent a backflow of a workingfluid from the collection manifold into the respective branch of theheat-transfer system.
 19. A rack-mountable server system according toclaim 11, further comprising a printed circuit board, wherein the sensorcomprises a sensitive region operatively coupled to the printed circuitboard at a position adjacent a component susceptible to wetting by theliquid if a leak of the liquid from the branch occurs.